Scientists in Australia and China have discovered how the body's "assassin" immunity cells memorise viruses, raising hopes for a life-long flu jab

A single vaccine that immunises against all types of influenza has come closer to being a reality, after scientists in Australia and China discovered how the body’s immunity cells remember flu viruses.

By studying patients infected with a deadly bird flu virus in China in 2013, scientists from the University of Melbourne and Fudan University in Shanghai discovered how the body’s “army of hitmen” T-cells memorise specific flu strains and destroy them.

The discovery, published in the journal Nature Communications on Wednesday, could lead to new cellular memory-implant technologies and a flu jab that would protect people for life.

The breakthrough came when scientists analysed patients who had contracted H7N9, a particularly deadly form of avian flu that first transferred to humans when an elderly man bought a chicken from a live poultry market in Shanghai.

“We’d never seen anything like H7N9,” said Katherine Kedzierska, associate professor at the University of Melbourne and one of the authors of the study.

Of the 602 people who have contracted H7N9, 38 per cent have died and almost all have been hospitalised with severe pneumonia or acute respiratory problems.

Ms Kedzierska continued: “Thankfully, we did manage to contain the virus but we knew we had come face-to-face with a potential pandemic that could kill millions of people around the world if the virus became able to spread between humans.”

After collecting samples from H7N9-infected patients the scientists found that people who couldn’t make the “flu assassin” CD8+T cells were dying. These T-cells are the “hitmen” of the immune system, efficiently eliminating virus-ridden cells.

This observation allowed scientists to crack the riddle of how these killer T-cells take out new viruses – by retaining “memories” of the virus strains they encounter.

The findings will enlighten T-cell based vaccine development, moving from vaccines targeting specific influenza to a universal protection.